Thiocarbamylsulfenamides are useful as accelerators for the sulfur vulcanization of unsaturated elastomers. The thiocarbamylsulfenamides are normally prepared by the reaction of a dithiocarbamate with an anime in the presence of an oxidizing agent. The resulting thiocarbamylsulfenamides, N,N'-[thiocarbonylthio]dimorpholine, for example, are normally not very storage stable, particularly under high temperature storage conditions that are often encountered under summer conditions or when exposed to other sources of heat. Under such conditions the thiocarbamylsulfenamide suffers degradation and a loss in activity. This results in slower cure rates and a decrease in scorch time.
A number of techniques to overcome this deficiency of the thiocarbamysulfenamides have been tried. Further processing of the thiocarbamysulfenamide with solvents and the like has been employed, but such processes are costly and have not been entirely satisfactory. Further, it would be desirable to eliminate having to handle a costly solvent and the subsequent processing steps, i.e., washing, filtration, drying, solvent recovery and purification and the like. Another approach has been by adding stabilizing materials to the thiocarbamylsulfenamides such as the oxirane compounds having molecular weights above 60 disclosed in U.S. Pat. No. 4,129,452 and the addition of certain acrylic amides and esters disclosed in U.S. Pat. No. 4,116,855. While this approach provided some stability to the thiocarbamylsulfenamides, the addition of these materials adds to the cost of the accelerator and introduces a foreign material in the thiocarbamylsulfenamide. Less expensive processes are still desirable that are incomplex.